LOS ANGELES (AP) — Detectives say the elementary school teacher told the children it was a game. Once inside his third-grade classroom, he blindfolded them, gagged them and set cockroaches crawling on their faces.

And then, Mark Berndt photographed them, creating hundreds of images that would eventually lead to his arrest.

On Tuesday, Berndt, 61, was sitting in jail on charges that he committed lewd acts on 23 boys and girls, ages 6 to 10, between 2008 and 2010. None of them complained about Berndt’s behaviour, authorities said.

Police and school officials only learned of it when a film processor found Berndt’s photos more than a year ago. Since the discovery, the school district fired Berndt and police put him under surveillance.

“If it wasn’t for the film processor, this could still be continuing today,” said Lt. Carlos Marquez of the Los Angeles County sheriff’s department.

Berndt was arrested Monday at his home in Torrance and was being held on $2.3 million bail.

Some parents picking up their pre-kindergarteners at the school on Tuesday complained that officials at Miramonte Elementary School in South Los Angeles should have notified them when the photos were found.

The probe began after the film processor, who is required by state law to report suspicions of child abuse and molestation, turned over some 40 photographs to authorities.